我的第四个程序 java实现加减乘除

import java.util.Scanner;

public class Test {


    public static void main(String [] args) { 


         Scanner sc = new Scanner(System.in); 

System.out.println("请输入算法："); 
         String go = sc.next();

         
System.out.println("请输入第一个数："); 
         Double a = sc.nextDouble(); 
         
System.out.println("请输入第二个数："); 
         Double b =  sc.nextDouble();


if(go.equals("+")){
    Double sum = a+b;
    System.out.println("他们的和为"+sum);
}

if(go.equals("-")){
     Double sum = a-b;
    System.out.println("他们的差为"+sum);
}

if(go.equals("*")){
     Double sum = a*b;
    System.out.println("他们的积为"+sum);
}

if(go.equals("/")){
    Double sum = a/b;
    System.out.println("他们的商为"+sum);
}

         

     
        
}
}